The lost hero The son of Neptune and the Mark of Athena

Each time the Argo II and the crew is about to reach Greece, something makes them go back. The most powerful demigods are trapped in Tartarus. The Doors of Death are wide open, so Gaea's army is almost invincible. They can't expect help from the camp, they are fighting their own battle against the romans. Every second they loose Gaea wakes up a little bit more. They cannot be more afraid. Also, they will find a fact that can start a civil war between the gods. What will they do? Enjoy, comment and vote!! All rights go to Rick Riordan this is just a fanfiction.